The present invention relates to apparatus for the lateral transfer of rod-like mandrels in a tube rolling mill.
More particularly, the invention is concerned with apparatus for the transfer of mandrels from the exit of a roller track of a mandrel lubrication station to a roller track of a station for the pre-insertion of the mandrels in respective axially pierced hot intermediate forgings to be conveyed to the tube rolling mill.
At the exit of a tube rolling mill of the type considered, the mandrels are extracted from the respective rolled tubes and are subjected to a whole series of treatments before being used in a new rolling cycle. These treatments are carried out in a series of appropriate stations, generally located upstream of the rolling mill. The last of these stations is a lube station from which the lubricated mandrels are taken by a roller track extending laterally of the rolling mill and parallel to the rolling axis. In the following description and in the subsequent claims, this roller track will be termed "the lube conveyor".
Before entering the rolling mill, the lubricated mandrels are pre-inserted in respective intermediate forgings at an appropriate pre-insertion station, at the entry to which each mandrel is supported by a roller track which may be in line with the rolling mill or may extend laterally thereof parallel to the rolling axis. In the following description and in the subsequent claims, this roller track will be termed: the pre-insertion line.
A transfer device provides for the transfer of the lubricated mandrels from the lube conveyor directly to the pre-insertion line.
It is known that, in order to make the best use of the capacity of a rolling mill of the type considered during a rolling cycle in which a mandrel is directly engaged, another three to five mandrels are distributed between the various treatment stations in a so-called "mandrel circulation". The number of mandrels and the times for treatment and transfer from one station to the other are calculated so that a lubricated mandrel is ready at the pre-insertion station when a rolled tube leaves the rolling mill.
In the present method of operation, in the event of accidental stoppage of the rolling mill, it is necessary to stop the mandrel circulation upstream of the rolling mill. This involves well known disadvantages both of a technical nature and of a strictly economic nature. For example, a more or less prolonged stoppage of the mandrels before the lubrication station may cause their temperatures to drop to values such that the lubricant does not adhere to them very well.
Consequently, the considerable forces to which the mandrels are subject during rolling may cause a noticeable reduction in the useful life of the mandrels.
The problem at the root of the present invention is that of overcoming the said disadvantages by providing apparatus having structural and functional characteristics such that it allows the treatments for the restoration of the mandrels for use in the rolling mill to be completed even in the event of an accidental stoppage of the rolling mill itself.